Loss of temperature sense or of the ability to distinguish between heat and cold; insensibility to heat or to temperature changes: Doug read a story about a strange person suffering from thermanalgesia and feeling neither cold nor hot temperatures.

A standard test of pain response involves applying heat to the skin, and most of us perceive pain when the skin reaches an average critical temperature of 113 degrees F (45 degrees C), and everyone, with the exception of people with serious sensory dysfunction, perceives pain before his or her skin reaches a temperature of 116.6 degrees F (47 degrees C).

Even though there are three to four times fewer heat receptors than cold receptors in the human skin, freezing cold and burning hot sensation are both experienced exactly the same. Indeed, at 140 degrees F (60 degrees C) both the cold and heat pain nerve endings are stimulated, and after a point, there is no reason to make fine distinctions—all the brain has to know is that it is very painful!